Dr. G.C. Dilsaver is rightly considered by many to be the father of Christian psychology, for his book Imago Dei Psychotherapy (IDP) enunciated the foundational principles of the first fully integrated Christian psychotherapeutic conceptualisation. The Imago Dei Psychotherapy (IDP) conceptualisation is based on the premise that the fullest understanding of human nature is found in traditional Christian, and especially Thomistic, anthropology, which delineates human moral action in its cognitive, volitional, and emotional elements. IDP maintains that locating the behavioural science of psychology within this traditional Christian anthropology of moral action unleashes that science's full and unprecedented clinical efficacy. Imago Dei Psychotherapy can be read with immense benefit not only by Catholics and Christians but by all who seek the most efficacious clinical means to mental health.